Improvement in duplex telegraphs



G. S. MOTT. Duplex Telegraphs.

No. %21,85O. Patented Nov 18, 1879.

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N. PETERS. FHOTO-LITHOGRAPHER, WASHINGTON. D10.

UNITED STATES FFroE.

PATET IMPROVEMENT IN DUPLEX TELEGRAPHS.

Specification forming part of Letters Patent No. 221,850, dated November18, 1879 application filed June 5, 1879.

posite ends of the line batteries of opposite polarity, which areconstantly in circuit through one or more (30118 of the relays, thesebatteries being arranged preferably between the grounds and the relays.

My invention also consists in combining with a home circuit and with thelinea relay composed of an armature and two independent magnets, one orboth of which can be adjusted, and both of which act on the armature inthe same direction. The short circuit is made through one magnet and theline-circuit through the other magnet of the relay; or the line-circuitmay be made through both magnets of the relay.

In the accompanying drawings, Figure l is a diagram of my improvedsystem of duplex telegraphy, and Fig. 2 a diagram of a modifiedarrangement.

It may be stated in the outset that the arrangement of transmitter,relay, and circuits contact-point is arranged to touch a contactpoint onthe end of the wire d, and make the ground-connection for the latterthrough the wire 0.

The wire (I is divided at as, so as to connect with the coils of twomagnets, a and. b, which, in connection with an armature, r, form therelay R. The wires of both magnets a and b are wound in the samedirection, and both act on the one armature of the relay in the samedirection 5 but the two magnets are independent of each other, and oneor both can headjusted by means of ordinary adjusting-screws r r. Thecoil to connects with the line L, while the coil 1) is in communicationwith the battery B through the wire 0, the battery being groundedthrough the wire f.

When the armature t of the transmitter is raised the battery isshort-circuited through the wire 0, magnet 1), wire (1, and wire 6 tothe ground. When the armature t of the transmitteris depressed thebattery is thrown on the line L through the wire 0 and both magnets toand 7).

Thebatteries, which are of oppositepolarity, are always in circuit, andare arranged at each station between the relay and the ground.

Inorder that the armature of the relay at the home station may not beaffected by the battery at the home station, but may be atfected by acurrent from the distant station, the spring of the armature and themagnet I) are so adjusted that when the home battery is short-ci'rcuitedthe effect on the armature will be nil, and the magnet to is also so adjusted in proportion to the resistance of the line that when the batteryis on the line the effect of both magnets, counteracted by theresistance of the line, will also be. practically nil, so that the homerelay will not be affected by the home'battery, no matter whether thelatter is on short circuit or on the line; but when the operator at thedistant station depresses his key a current from his battery will bethrown on the line, and the combined effect of the two batteries on themagnet or magnets of the relay at the home station will cause theattraction of the armature, and thus record the signals from the distantstation, whether the operator at the home station is working histransmitter or not.

The arrangement shown in the diagram, Fig. 2, is substantially the sameas that shown in Fig. 1, except that the positions of the magnets a andb at each station are changed, so that while the short circuit is madethrough the magnet b, as before, the line-circuit is made through themagnet to only, instead of through both magnets. This necessitates asomewhat difierent adjustment of the magnets in respect to the armature;but the operation is the same as that described above.

In order to prevent a too rapid consumption of the battery when thelatter is short-circuited, I prefer to arrange 0n the wire 0 a smallresistance-box, It It. A small resistancebox may be put on the wire 61,so as to insure a slight leakage onto the line L.

It will be seen, however, that the large rheostats by which the requiredbalance of the armature of the relay is usually obtained are dispensedwith, and that in my system the balance is obtained by means of theindependent adjustable magnets arranged as described. Moreover, owing tothe absence of these large rheostats almostthe entire effect of thebatteries is utilized for working the line.

If desired, a key may be substituted for the transmitter at the homestation, and the signals will thus be made by drawing the battery offthe line by the depression of the home key,

instead of by the raising of the transmitterarmature, in which case thesignal would have to be given on the back stroke of the armature of therelay at the distant station.

The line may be singled up for ordinary Morse transmission by closingthe-local key, thus pressing down the armature of the transmitter, andconnecting a key, K, with theline c, as indicated by dotted lines inFig. 1.

I claim as my invention- 1. A duplex-telegraph system in which thearmature of the relay is combined with two independent magnets, one orboth of which are adjustable, and both of which are arranged to act onthe said armature in the same direction, all substantially as described.

2. In a duplex-telegraph system, the combination of the line and shortcireuitswith relays, each consisting of two independent adjustablemagnets and an armature, vthe short circuit being made through onemagnet and the line circuit through the other magnet, or through bothmagnets, of the relay, as set forth.

3. A duplex-telegraph system in which the batteries of opposite polarityat opposite ends of the line are constantly in circuit through one ormore coils of the relays.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

' G. S.'MOTT.' Witnesses:

WILLIAM J. OooPER, HARRY SMITH.

